Pulse amplitude discriminator



June 4, 1963 J. BAUDE PULSE AMPLITUDE DISCRIMINATOR Filed Feb. 24, 1959 Patented June 4, 1.963

3,092,731 PULSE AMPLITUDE DSCRIMINA'IOR John Bande, Milwaukee, Wis., assigner to Ailis-Chalmers Manufacturing Company, Milwaukee, Wis. Filed Feb. 24, 1959, Ser. No. 794,965 14 Claims. (Cl. 307-885) This invention relates to circuits responsive to predetermined pulse amplitude and more particularly to triggering circuits wherein pulses of a source are transmitted as a function of voltage amplitude to a device for controlling a load.

The circuits disclosed were provided to detect at least a two millisecond current pulse and transmit it as a function `of voltage amplitude to a transistor arrangement which would energize a trip structure for circuit breaker operation.

ln accordance with the invention claimed a new and improved triggering circuit is provided which is responsive to a predetermined pulse amplitude. This circuit is connected across a source of electric pulses and comprises a transformer having a primary winding and a secondary winding, said primary winding being connected across the source of pulses, a voltage responsive means connected in series with the primary winding for transmitting to the primary winding pulses of the source as a function of voltage amplitude and a pulse responsive electric device connected across the secondary winding for controlling a load.

Itis, therefore, one object of this invention to provide a new and improved pulse amplitude discriminating circuit.

Another object of this invention is to provide a new and improved triggering circuit in which pulses of a source are transmitted as a function of voltage amplitude.

A further object of this invention is to provide a new and improved triggering circuit in which a transistor switching arrangement is triggered by pulses of only a certain amplitude.

Objects and advantages other than those set forth will be apparent from the following description when read in connection with the accompanying drawing, in which:

fFIG. l is a schematic view of an improved pulse amplitude discriminating circuit embodying the invention;

FIG. 2 is a modication of the circuit shown in FIG. 1 and embodying the invention; and

FIG. 3 is a partial view of a modification of the circuit illustrated in FIGS. l and 2 and embodying the invention.

Referring more particularly to the drawing wherein like parts are designated by like characters of reference throughout the gures, FIG. 1 illustates a pulse amplitude i discriminating circuit 10 which may be, for example, utilized for triggering a high speed circuit breaker tripping mechanism 11. In the circuit illustrated the pulse amplitude discriminator circuit is utilized to detect a two millisecond current pulse taken from a shunt 12 in a klystron radar application. The klystron tube is a transmitting mechanism which may be triggered thirty times a second and is usually capable of carrying thirty ampere square shaped current pulses. This type of tube is readily destroyed if subjected to current pulses of an amplitude greater than its rating and in view of its cost must be accurately controlled. Therefore, the claimed invention was conceived to rst detect a dangerous electrical condition and second to trigger a high speed electronic trip mechanism into conduction and by action of this mechanism trip a high speed circuit breaker controlling the energization of the klystron tube.

A voltage signal from shunt 12 connected to the klystron tube (not shown) is transmitted by means of a pair of shielded cables 13, 14 across a potentiometer 15. The voltage pulse appearing across potentiometer 15 is trans'- `mitted by means of a slider 16, resistor 17 and parallelly connected voltage responsive impedance means such as Zener diodes 18, 19 and 20 each connected in series with resistors 21, 22 and 23, respectively, to a terminal 24 of a primary winding 25 of a transformer 26 and through a conductor 27 to the other terminal 28 of transformer 26. Although three Zener diodes are shown only one or more may be used. Zener diodes 18, 19 and 20 comprise nonlinear voltage limiting breakdown devices.

The maximum voltage which appears across resistors 21, 22 and 23 and terminal 28 of transformer 26 is limited by an impedance device such as a varistor 29 which is connected between resistor 17 and the parallel arrangement of resistors 21, 22 and 23 'and conducto-r 27 between the connection of rheostat 15 and terminal Z8 of transformer 26. Varistor 29 is a nonlinear voltage regulating device which limits the maximum voltage to a given value, i.e., the greater the voltage the more current that is carried by the varistor resulting eventually in an equilibrium condition between the voltage drop and current ow across and through the varistor. lPotentiometer 15 is adjusted or varied to match the voltage responsive characteristics of the Zener diodes 18, 19 and 20.

Upon the application of a voltage pulse to the varistor greater than the voltage rating of the Zener diodes 18, 19 and 2), current will pass at that instant through these Zener diodes, the primary winding 25 of transformer Z6 and back to shunt 12. The pulse applied to primary winding 25 of transformer 26, which in the example being explained is a two millisecond square pulse, is induced into its secondary winding 30.

The secondary winding 3G of transformer 26 is connected across a high speed pulse responsive electric device 33 for controlling the tripping mechanism 11 of a circuit interrupting device. Device 33 comprises a pair of complementary semiconductor devices such as, for example, transistors 34 and 35 directly coupled in a cascaded system, or an avalanche type semiconductor device such as the unijunction transistor. Transistors 34 and 35 each comprise bases 36, 37, collectors 313, 39 and emitters 40, 41, respectively. The emitters and collectors of each transistor are connected in different series circuits 43, 44 across a source of potential such as a direct current source 45, 46. The terminal 45 of the direct current source is connected through a conductor 47 and a conductor 4.3 to a terminal 49 of the secondary winding 3i) of transformer 26, and through conductor 47, a conductor 5), resistor 51 to the terminal 2S of the primary winding 25 of transformer 26. Base 36 of PNP transistor 34 is connected through a conductor 53, a diode 54 and a conductor 55 to a terminal 56 of secondary winding 36 of transformer 26. Base 37 of NPN transistor 35 is connected through a conductor 57 and resistor 58 to circuit 43 and collector 33 of transistor 34. A diode 59 is connected in circuit 43 between conductor 47 and emitter 4i) of transistor 34, and a diode 6l) is connected in circuit 44 between emitter 41 of transistor 35 and a conductor 61 connected to terminal 46 of the direct current source.

Resistors 62 and 63 are connected between emitters il? and 41 and conductors 61 and 47, respectively. Diodes 59, 69 and resistors 62, 63 are utilized to provide transistors 34 and 3S with negative or reverse bias. The voltage drop which occurs across these diodes helps keep transistors 34 and 35 at cutol and render them temperature stable. A capacitor 64 connected between emitter di) and base 36 of transistor 34 is utilized to prevent spurious voltage surges from triggering into conduction transistor 34 prematurely. Capacitor 65 connected between conductors 47 and 61 is used to neutralize any voltage surges that may build up between terminals 45 and 46 of that direct current source.

An adjustable resistor 66 connected across the terminals V24, 28 of the primary winding 25 of transformer 26 is utilized to discharge the primary winding of transformer 25 rapidly so as to render the tripping circuit responsive to a plurality of sequential voltage pulses. Resistor `51 and capacitor 68 are connected between terminal 2S of the primary winding 25 of transformer 26 and conductor 47 to bring Vthe potential of the grounded cable 14 close to the positive terminal 45 of the ungrounded direct current source. This type of connection avoids the possibility of surge transmittal from the ungrounded direct current source 45, 46 to the grounded source of pulses from cables 13, 14 by making the potential difference between these sources as small as possible at the most sensitive point of the circuit, namely at the point of connection of the positive terminal 45 of the direct current source to the secondary Winding 30 of the transformer 26. As noted the secondary winding 30 is connected through conductor 55, diode 54, 'conductor 53, base 36 and emitter 4t) of transistor 34, diode 59 and conductor 47 to the positive terminal 45 of the direct current source.

When an input voltage signal of, for example, two milliseconds exceeding the rating of the Zener diodes 18, 19 and 20 is applied to shunt 12 the pulse enters the primary winding of transformer 26 and is transmitted as a function of voltage amplitude to its secondary winding 33. The resultant pulse of the secondary winding 3i) is applied through diode 54 to the base 36 of transistor 34. The pulse renders transistor `3d temporarily cndnctive. As a resuit current passes from the positive terminal 45 of the directcurrent source through diode 59, emitter 4t? and collector 3S of the transistor 3ft-,through a resistor 'lil to the negative terminal 46 of the"direct current source. When this happens Voltage builds up across resistor 7i? and is applied by means of resistor 58 to the base 37 of transistor 35. Transistor 3S is then rendered conductive and passes current from the positive terminal 45 of the direct current source through a resistor 71, collector 39 and emitter 41 of transistor 35 and diode 69, conductor 61 to the negative terminal 46 of the direct current source. The voltage build-up across resistor 71 is applied to the input terminals of an electronic trip device or mechanism -11 connected across a source of electric power such as terminals 45, 46. The electronic trip device 11 is triggered into conduction and by means of its action the circuit breaker is tripped which controls the energization of the klystron tube.

The above described circuit is so fast acting that if a surge pulse fed to the klystron tube starts at a safe level and continues for a while and then increases in amplitude during the last half of the two millisecond pulse to an unsafe value the circuit will respond and trip the circuit breaker to disconnect the klystron tube from its energizing circuit.

The voltage or current sensing Icircuit disclosed in FIG. l has a lock in characteristic. When transistor 34 is energized into conduction the voltage drop across resistor 751 renders transistor 35 conductive `and when transistor 35 conducts its action keeps the base 36 ofY transistor 34 suticiently negative to insure continuous conduction of both transistors 34 and 35 until the circuit breaker has interrupted the energizing circuit for the klystron tube.

FIG. 2 illustrates a pulse amplitude discriminating device similar to that shown in FIG. l wherein one semiconductor device is used to trigger the high speed trip mechanism 1'1 `for disconnecting by -means of a circuit breaker Ythe klystron tube from its energizing circuit. When the primary winding 25 of transformer 26 receives a pulse from shunt 12 in the same manner as described in FIG. l the `secondary Winding through the diode 73 renders transistor 35 conductive and current flow occurs from terminal 45 of the direct current source through resistor 71, collector 39 and emitter 41 of transistor 35, diode `6i) and conductor 61 to the other terminal 46 of the direct current source. The voltage build-upV across resistor 71 is applied to the input terminals ofthe electronic trip mechanism 11 connected across terminals 72, 46 and triggers mechanism V11 to open a circuit breaker controlling the energization of the klystron tube.

The lock in feature of the circuit illustrated in FIG. 1 is omitted in the structure shown in FG. 2, however, it may be built in another part of -the control circuit such as the ultra high speed trip mechanism 11.

The circuits illustrated in FIGS. land 2 will respond to unidirectional positive pulses. If it is desired that the pulse amplitude discriminator disclosed respond to pulses of alternating polarity then the circuits illustrated'in FIGS. 1 and 2 should be modified as shown in FIG 3.

FIG. 3 utilizes idouble anode Zener diodes 75, 76 and 77 in place of Zener diodes 18, 19 and 20 and a varistor 73 connected in parallel with varistor 29 but connected in opposite polarity thereto.

Although but a few embodiments `of the present invention have been illustrated and described it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of 4the invention or from the scope of the appended claims.

Having now particularly described and ascertained the nature of my said invention and the manner in which it is to tbe .per-formed, I declare that what I claim is:

1. A triggering circuit responsive to a predetermined -pulse amplitude comprising a sourceof electric oscillations, a transformer comprising a primary winding, said primary winding kbeing connected across said source of oscillations, an adjustable impedance connected in -shunt across said source of oscillations and said primary winding, a voltage responsive impedance means comprising a semiconductor having a very high Voltage characteristic in one operating range and a very loW voltage operating characteristic in another range, connected in series with said primary winding for transmitting the oscillations of said source as a function of voltage amplitude, said adjustable impedance being varied to match the voltage responsive impedance means rating.

2. A triggering vcircuit responsive to a predetermined pulse amplitude comprising a source of electric pulses, a transformer comprising a primary winding, said primary winding being connected across said source of pulses, an adjustable impedance connected in shunt across said source of pulses `and said primary winding, a Zener breakdown diode connected in series with said primary Winding for transmitting the pulses of said ysource as a func- -tion of voltage amplitude, said adjustable impedance being variedrto match the voltage ,responsive characteristics of said Zener diode.

3. A triggering circuit responsive to a predetermined pulse amplitude comprising a source of electric pulses, a transformer comprising a primary winding, said primary winding being connected across said source of pulses,an impedance connected in shunt across said source of pulses and said primary winding, said 4impedance vcomprising a nonlinear voltage limiting device, and a voltage responsive impedance means connected in series with lsaid primary winding .for transmitting to said primary winding pulses of said source as a function of voltage amplitude.

4. A triggering circuit responsive to a predetermined pulse amplitude comprising a source of electric pulses, a transformer comprising a primary winding, said primary Winding being connected across said source of'pulses, a iirst adjustable impedance connected in -shunt across said source of pulsesV and said primary winding, a second impedance connected in shunt across said source of pulses and said primary winding, said second impedance comprising a nonlinear voltage limiting device, and a Zener breakdown diode connected -in series with `said primary winding for transmitting the pulses of said source as a function of voltage amplitude, said adjustable impedance being varied to match the voltage responsive character- Y istics of said Zener diode.

5. A triggering circuit responsive to a predetermined pulse amplitude comprising a source of electric pulses, a transformer comprising a primary Winding and a secondary winding, said primary winding being connected across said source of pulses, an impedance connected in shunt across said source of pulses and said primary winding, said impedance comprising a nonlinear voltage limiting device, a voltage responsive impedance means connected in series with said primary -winding for transmitting the pulses of said source as a function of voltage amplitude, and a pulse responsive electric 4device connected across said secondary winding for controlling a load.

6. A triggering circuit responsive to a predetermined pulse amplitude comprising a source of electric pulses, a transformer comprising a primary winding and a secondary winding, said primary winding being connected lacross said source of pulses, a first adjustable impedance connected in shunt across said `source of pulses and said primary winding, a second impedance connected in shunt across said source of pu-lses and said primary winding, said second impedance comprising a nonlinear voltage 4limiting device, `a Zener breakdown diode connected in series with said primary winding for transmitting the pulses of said source as a function of voltage amplitude, a resistor connected in series with said diode between said second impedance and said diode for limiting the voltage drop across said diode, and a pulse responsive electric device connected across said secondary winding for controlling `a load.

7. A triggering circuit responsive to a predetermined pulse amplitude comprising a source of electric pulses, a transformer comprising a primary winding and a secondary winding, said primary winding being connected across said source `of pulses, a first resistor connected in shunt across said primary winding, a first adjustable impedance connected in shunt across said source of pulses and said primary winding, a second impedance connected in shunt `across said source of pulses and said primary winding, said second impedance comprising `a nonlinear voltage limiting device, a Zener breakdown diode connected in series with said primary winding for transmitting the pulses of said source as a function of voltage amplitude, a second resistor connected in series with said diode between said second impedance and said diode for limiting the voltage drop across said diode, and a pulse responsive electric device connected across said secondary winding for controlling a load, said rst resistor dischanging rapidly said primary winding after each surge applied thereto. v

S. A triggering circuit responsive to a predetermined pulse amplitude comprising a source of electric pulses, a transformer comprising a primary winding and a secondary winding, said primary winding being connected across said source of pulses, a lirst adjustable impedance connected in shunt across said `source of pulses and said primary winding, a second impedance connected in shunt across said source of pulses and said primary winding, said second impedance comprising a nonlinear voltage limiting device, more than one Zener breakdown diode connected in parallel with each other and in series with said primary winding for transmitting t-he pulses of said source as a function of voltage amplitude, a resistor connected in series with each of said diodes between said -second impedance and said diodes for limiting the voltage drop across said diodes, and a pulse responsive electric device connected across said secondary winding for controlling a load.

9. A triggering circuit responsive to a predetermined pulse amplitude comprising a source of electric pulses, a transformer comprising a primary winding and a secondary winding, said primary winding being connected across said source of pulses, a first resistor connected in shunt across said primary winding, a first adjustable impedance connected in shunt across said source of pulses and said primary winding, a second impedance connected in shunt across said source of pulses and said primary Winding, said second impedance comprising a nonlinear voltage limiting device, a plurality of Zener breakdown diodes connected in parallel with each other and in series with said primary winding for transmitting the pulses of said source as a function of voltage amplitude, a second resistor connected in series with each of said diodes between said second impedance and said diodes for limiting the voltage drop across said diodes, and a pulse responsive electric device connected `across said secondary Winding for controlling a load, said first resistor discharging rapidly said primary winding after each surge applied thereto.

l0. A triggering circuit responsive to a predetermined pulse amplitude comprising a source of electric pulses, a transformer comprising a primary winding and a secondary winding, said primary winding being connected across said source of pulses, an impedance connected in shunt across said source of pulses and said primary windin-g, -said impedance comprising a nonlinear voltage limiting device, a voltage responsive impedance means connected in series wit-h said primary winding for transmitting to said primary winding pulses of said source as a function of voltage amplitude, and a pulse responsive electric device `comprising a pair of complementary transistors directly coupled in `a cascaded system across said secondary winding for controlling a load.

ll. A triggering circuit responsive to a predetermined pulse amplitude comprising a source of electric pulses, a transformer comprising a primary winding and a secondary Winding, said primary winding being connected across said source of pulses, a voltage responsive impedance means connected in series with said primary winding for transmitting to said primary winding pulses of said source as a function of voltage amplitude, and a pulse responsive electric device connected across said secondary winding for controlling a load, said device comprising a pair of complementary transistors directly `coupled in a cascaded system, each of said transistors comprising a base, collector and emitter, a source of potential, said emitter Iand collector of each of said transistors being connected in a different series circuit across said source of potential, each of said series circuits being connected at one end thereof to one terminal of said secondary winding, said base of one of said transistors being connected to the other terminal of said secondary Winding, said base of said other transistor being connected to said collector of said one of said transistors, said collector of said other of said transistors being connected to said base of said one of -said transistors, said one of said transistors upon a change of base potential upon receiving a pulse from said secondary winding energizing said one of said transistors causing current to pass through its emitter, collector series circuit to the load, said current changing the potential of said base of said other transistor causing current to ow through its emitter, collector series circuit, said latter current flow retaining transistor conducting potential on said base of said one of said transistors, and means for disconnecting said source of potential Vfrom said one of said transistors for causing said transistors to become nonconductive.

12. A triggering circuit responsive to a predetermined pulse amplitude comprising a source of electric pulses, a transformer comprising a primary winding and a secondary winding, said primary winding being connected across said source of pulses, an adjustable impedance connected in shunt across said source of pulses and said primary winding, a voltage responsive impedance means connected in series with said primary winding for transmitting to said primary winding pulses of said source as a function of voltage amplitude, and a pulse responsive electric device connected across said secondary winding for controlling a load, said device comprising a pair of complementary transistors directly coupled in a cascaded system, each of said transistors comprisinga base, collector and emitter, a source of potential, said emitter and collector of each of said Ytr-ansistors being connected in a different series circuit across said source of potential, each of said series circuits being connected at one end thereof to one terminal of said secondary winding, said base of one of said transistors being connected to the other terminal yof said secondary Winding, said base of said other transistor being connected to said collector of said one of said transistors, said collector of said other of said transistors being connected to said base of said one of said transistors, said one of said transistors upon a change of base potential upon receiving a pulse from said secondary winding energizing said one of said transistors causing current to pass through its emitter, collector series circuit to the load, said current changing the potential of said base of said other transistor causing `cur-rent to flow through its emitter, collector series circuit, saidV latter current flow retaining transistor conducting potential on said base of said one of said transistors, and means for Vdisconnecting said source of potential from said one of vage amplitude, -said adjustable impedance being varied to 'match the voltage responsive characteristics of said Zener diode, and a pulse responsive electric device connected across said secondary Winding for controlling a load, said device comprising a pair of complementary transistors directly coupled in a cascaded system, each of said transistors comprising a base, collector and emitter, a source of potential, said emitter and collector of each of said transistors being connected in a different series circuit across said source of potential, each of said series circuits being connected -at one end thereof to one termi-nal of said secondary Winding, said base of one of said transistors being connected to the other terminal of said secondary Winding,V said base of said other transistor being connected to said collector of said one of said transistors, said co1- lector of said other of said transistors being connected to said base of said one of said transistors, said one of said transistors upon a change of base potential upon receiving a pulse from said secondary Winding energizing said one of said transistors causing current to pass through its emitter, collector series `circuit .to the load, said current changing the potential Vof said base of said other transistor causing current to ow through its emitter, collector series circuit,

said latter current flow retaining .transistor conducting potential on said base of said one of said transistors, and means for disconnecting said source of potential .from said one Vof said transistors for causing said transistors to kbecome nonconductive. v

14. A triggering circuit responsive to a predetermined pulse amplitude comprising a source of electric pulses, a transformer comprising'. a primary Winding and a secondary Winding, said primary Winding being connected across said source of pulses, a voltage responsive impedance means connected in series with said primary Winding for transmitting to said primary winding pulses of said source as a function of lvoltage amplitude, and a pulse responsive electric device connected across said secondary Winding for controlling a load, said device comprising a pair of complementary transistors directly coupled in a cascaded system, each of said transistors comprising a base, collector and emitter, a source of potential, said emitter and collector of each of said transistors being connected in a series circuit across said source of potential, each of said series circuits being connected at one end thereof to the positive terminal Vof said secondary winding, a pair-of diodes one `being connected adjacent the emitter in each series circuit lfor driving the potential `of the base of the transistor associated Wit-h the emitter of said circuit beyond cutoff thereby ltemperature stabilizing said transistor, said base of one of said transistors being connected to the negative terminal 'of said secondary Iwinding, said base of said other transistor being connected to said collector of said one of said transistors, said collector of said other or" said transistors being Yconnected tosaid base of said one of said transistors, said one of said transistors upon a change of base potential upon receiving a pulse from said secondary Winding energizing Vsaid ione of said transistors causing current to pass through its emitter, collector series circuit to the load, said current changing the potential of said base of said other transistor causing current to flow through its emitter, collector series circuit, said latter current oW retaining transistor conducting potential on said base of said one of said transistors, and means for disconnecting said source of potential from said one of said transistors for causing said transistors to become nonconductive.

References Cited in the tile of this patent 

1. A TRIGGERING CIRCUIT RESPONSIVE TO A PREDETERMINED PULSE AMPLITUDE COMPRISING A SOURCE OF ELECTRIC OSCILLATIONS, A TRANSFORMER COMPRISING A PRIMARY WINDING, SAID PRIMARY WINDING BEING CONNECTED ACROSS SAID SOURCE OF OSCILLATIONS, AN ADJUSTABLE IMPEDANCE CONNECTED IN SHUNT ACROSS SAID SOURCE OF OSCILLATIONS AND SAID PRIMARY WINDING, A VOLTAGE RESPONSIVE IMPEDANCE MEANS COMPRISING A SEMICONDUCTOR HAVING A VERY HIGH VOLTAGE CHARACTERISTIC IN ONE OPERATING RANGE AND A VERY LOW VOLTAGE OPERATING CHARACTERISTIC IN ANOTHER RANGE, CONNECTED IN SERIES WITH 